The present embodiments relate to capacitive membrane ultrasound transducers (cMUT). A cMUT includes an array of elements. Each element includes a plurality of cells of microelectromechanical devices, such as membranes with an associated chamber or gap. The membranes lay in a plane along an emitting face of the element. Electrodes are provided adjacent the membrane and away from the membrane in the chamber. In response to alternating electrical potential, the membranes flex in or out of the plane, causing rarefaction and pressure waves that propagate along a range dimension orthogonal to the plane. In response to acoustic waves, the membranes flex, causing changes in electrical potential between the electrodes.
The cMUT may generate a far-field pressure of 1 MPa at 10 MHz with a peak membrane or diaphragm excursion of about 0.03 μm. Low frequency, higher power applications, such as bubble bursting or harmonic imaging, may operate with 3 MPa at 1 MHz. For these pressures, the peak membrane excursion may be around 1 μm or more. A cMUT and associated membranes may not be able to satisfy such a high-pressure requirement.